from typing import List, Tuple


def floyd_warshall(n: int, graph: List[List[int]]) -> List[List[int]]:
    dist = [[float("inf")] * n for _ in range(n)]
    for i in range(n):
        dist[i][i] = 0
    for u in range(n):
        for v, w in enumerate(graph[u]):
            if w != 0:
                dist[u][v] = w
    for k in range(n):
        for i in range(n):
            for j in range(n):
                dist[i][j] = min(dist[i][j], dist[i][k] + dist[k][j])
    return dist


def solve_case(w: int, e: int, c: int, west: List[int], east: List[int], queries: List[Tuple[int, int]]) -> List[float]:
    graph = [[0] * (w + e) for _ in range(w + e)]
    for i in range(w - 1):
        graph[i][west[i] - 1] = 1
        graph[west[i] - 1][i] = 1
    for i in range(e - 1):
        graph[i + w][east[i] - 1 + w] = 1
        graph[east[i] - 1 + w][i + w] = 1

    dist = floyd_warshall(w + e, graph)

    ans = []
    for i in range(c):
        u, v = queries[i]
        u -= 1
        v -= 1 + w
        graph[u][v] = 1
        graph[v][u] = 1
        new_dist = floyd_warshall(w + e, graph)
        total_dist = sum(sum(new_dist[u]) for u in range(w + e))
        ans.append(total_dist / ((w + e) * (w + e - 1)))
        graph[u][v] = 0
        graph[v][u] = 0

    return ans


t = int(input())
for i in range(1, t + 1):
    w, e, c = map(int, input().split())
    west = list(map(int, input().split()))
    east = list(map(int, input().split()))
    queries = [tuple(map(int, input().split())) for _ in range(c)]
    ans = solve_case(w, e,